1. Field of the Invention
This invention relates to an improved solid adhesive, and in particular to such a solid adhesive which has good formability or shapability and can be formed into a stick which has a small diameter while having a unique combination of bending strength and crush strength at a room temperature.
2. Description of the Prior Art
There have been proposed various adhesives which are in solid states at a room temperature. For example, Japanese patent publication No. 34581/1975 discloses a solid adhesive which comprises a mixture of adhesive resins, benzylidene sorbitol, water and/or organic solvents. Japanese patent publication No. 25830/1984 relates to an improvement of the adhesive disclosed in Japanese patent publication No. 34581/1975, and discloses a solid adhesive which comprises adhesive resins, dibenzyliden (penta or hexa hydric) saccharide, water and organic solvents containing 3-methyl-3-methoxy-1-butanol. Japanese patent publication Nos. 34581/1975 and 25830/1984 are incorporated herein by reference (hereinafter referred to as "References").
This type of solid adhesive can be formed into a variety of shapes for a wide variety of uses. Recently, there is proposed a pen-type dispenser for selectively extending and retracting a stick-shaped object, e.g., a stick-shaped rubber eraser, a stick-shaped adhesive, a rouge or eyebrow pencil, or the like. The pen-type dispenser is disclosed in Japanese utility model provisionary publication No. 74382/1994 which is incorporated herein by reference. This type of dispenser is slim-sized and handy to carry. Therefore, in this field, a stick-shaped object is required to have the smallest diameter possible, and required to have good bending strength and crush strength at a room temperature. Particularly, a stick-shaped solid adhesive is required to have a diameter of not more than about 0.47 inch (12 mm.) and required to have bending strength of not less than about 1.5 N (newton) and crush strength of not more than about 12 times as large as the bending strength at a room temperature.
Commercial grades of solid adhesives and the solid adhesives disclosed in the References can be formed into sticks each having a large diameter or a minimum diameter of about 0.62 inch (16 mm.), but can not be formed into sticks each of which has a smaller diameter while having good shape-maintainability, bending strength and crush strength at a room temperature.
Thus, it would be highly desirable to have a solid adhesive which has good formability or shapability and can be formed into a stick having a small diameter while having a unique combination of shape-maintainability, bending strength, and crush strength.